Khatta 2000.

Study characteristics
Methods	RCT with parallel design
Participants	55 participants who had congestive heart failure with NYHA class III and IV symptoms to receive either coenzyme Q10 200 mg/day or placebo for a period of 6 months 28 in the treatment group and 27 in the placebo group Adults (> 18 years)
Interventions	Intervention: oral coenzyme Q10 200 mg/day Control: placebo
Outcomes	Left ventricular ejection fraction (measured by radionuclide ventriculography) Peak oxygen consumption
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was performed using a random number generator
Allocation concealment (selection bias)	Unclear risk	No information given
Blinding of participants and personnel (performance bias) All outcomes	Low risk	All participants and study personnel were blinded to study group assignment until all data were final Double‐blind
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information given
Incomplete outcome data (attrition bias) All outcomes	High risk	9 participants did not finish the study: 5 in the coenzyme Q10 group and 4 in the placebo group.
Selective reporting (reporting bias)	Unclear risk	No study protocol was available.
Other bias	Low risk	No other bias could be found